The textbook by Prof. Dr.-Ing. Siegfried Hildebrand: "Feinmechanische Bauelement", VEB Verlag Technik Berlin, 4th edition, 1980, pages 677 describes centrifugal-braking-force regulators which have lever-mounted centrifugal weights and in which the centrifugal force acts against the resetting force of a compression spring arranged axially relative to the stroke axis. The effectiveness of the regulator starts from a limit speed at which the braking surfaces are just in contact. The spring force increases with increasing stroke.
An automatically resetting safety valve requires rapid opening on the one hand and wide opening on the other hand, even if the valve-opening force, after reaching a release force, does not increase substantially over the stroke of the valve or even decreases.